\documentclass{book}
\usepackage{tikz}
\usetikzlibrary{tikzmark, calc}
\usepackage{array}
\usepackage{multirow}
\renewcommand{\arraystretch}{1.4}
\begin{document}
\begin{tabular}{ccc}
	\multicolumn{2}{c}{\tikzmark{cmc}\hfill A and B\hfill\null} & C\tikzmark{dmc} \\
	D wider & E                                                 & F               \\
\end{tabular}
\begin{tikzpicture}[overlay,remember picture]
	\draw (pic cs:cmc) -- (pic cs:dmc);
\end{tikzpicture}
\end{document}
